Computer modeling shows that the Wright's propeller design was almost optimal for their low airspeed.
Computer modeling shows nothing because the alleged 1903 originals have not survived, excepting some badly damaged parts.
The site
Mechanical Engineering "100 Years of Flight" supplement, Dec. 2003 -- "Prop-Wrights," Feature Article says that many tests were effectuated and efficiencies between 75% and 82% were obtained, which is not 66% as the Wright brothers claimed. The same site says
the propellers were reconstructed, with the help of computers,
starting from badly damaged parts of the originals. However, in their reconstructions, the people who recreated them acknowledged they had made some assumptions that could have alter the efficiency.
see also:
http://www.pprune.org/aviation-histo...ml#post8496921